Thermal conductivity of suspended GaN thin film measured by Raman spectroscopy

Abstract

With the increasing power density and shrinking size of GaN electronic devices, nanometer-scaled thermal management is becoming a key issue. However, the thermal conductivity (κ) estimation of the sub-100 nm-thick GaN is challenging due to its poor quality on foreign substrates and measurement limitations. Here, we introduce a substrate-free suspended structure measured by Raman spectroscopy. The suspended sub-100 nm GaN thin films are obtained with a release process by using a lattice-matched Al_0.83In_0.17N as a sacrificial layer on high-quality GaN templates. The local temperature rise by Raman spectroscopy at the bridge center is forced to propagate in-plane toward the anchor, and the κ is thus obtained through analyzing the Raman shift dependent on the temperature and power density. This result is helpful for the design and nanometer-scaled thermal management of the current GaN-based power electronic devices.